Semiconductor devices are commonly found in modern electronic products. Semiconductor devices vary in the number and density of electrical components. Discrete semiconductor devices generally contain one type of electrical component, e.g., light emitting diode (LED), small signal transistor, resistor, capacitor, inductor, and power metal oxide semiconductor field effect transistor (MOSFET). Integrated semiconductor devices typically contain hundreds to millions of electrical components. Examples of integrated semiconductor devices include microcontrollers, microprocessors, charged-coupled devices (CCDs), solar cells, and digital micro-mirror devices (DMDs).
Semiconductor devices perform a wide range of functions such as high-speed calculations, transmitting and receiving electromagnetic signals, controlling electronic devices, transforming sunlight to electricity, and creating visual projections for television displays. Semiconductor devices are found in the fields of entertainment, communications, power conversion, networks, computers, and consumer products. Semiconductor devices are also found in military applications, aviation, automotive, industrial controllers, and office equipment.
Semiconductor devices exploit the electrical properties of semiconductor materials. The atomic structure of semiconductor material allows its electrical conductivity to be manipulated by the application of an electric field or base current or through the process of doping. Doping introduces impurities into the semiconductor material to manipulate and control the conductivity of the semiconductor device.
A semiconductor device contains active and passive electrical structures. Active structures, including bipolar and field effect transistors, control the flow of electrical current. By varying levels of doping and application of an electric field or base current, the transistor either promotes or restricts the flow of electrical current. Passive structures, including resistors, capacitors, and inductors, create a relationship between voltage and current necessary to perform a variety of electrical functions. The passive and active structures are electrically connected to form circuits, which enable the semiconductor device to perform high-speed calculations and other useful functions.
Semiconductor devices are generally manufactured using two complex manufacturing processes, i.e., front-end manufacturing, and back-end manufacturing, each involving potentially hundreds of steps. Front-end manufacturing involves the formation of a plurality of die on the surface of a semiconductor wafer. Each die is typically identical and contains circuits formed by electrically connecting active and passive components. Back-end manufacturing involves singulating individual die from the finished wafer and packaging the die to provide structural support and environmental isolation.
One goal of semiconductor manufacturing is to produce smaller semiconductor devices. Smaller devices typically consume less power, have higher performance, and can be produced more efficiently. In addition, smaller semiconductor devices have a smaller footprint, which is desirable for smaller end products. A smaller die size may be achieved by improvements in the front-end process resulting in die with smaller, higher density active and passive components. Back-end processes may result in semiconductor device packages with a smaller footprint by improvements in electrical interconnection and packaging materials.
FIG. 1a shows a conventional flipchip type semiconductor die 10 with active surface 12. Semiconductor die 10 is originally formed on a wafer. An electrically conductive layer 14 is formed over active surface 12. Conductive layer 14 provides electrical interconnect for the circuits on active surface 12. A passivation layer 16 is formed over active surface 12 and conductive layer 14. An under bump metallization (UBM) 18 is formed over conductive layer 14 and passivation layer 16. A conductive pillar 20 is formed over UBM 18 and a solder cap is formed over conductive pillar 20. The solder cap is reflowed to form a rounded solder bump 22, typically while semiconductor die 10 is in wafer form.
Substrate 24 includes horizontal conductive layers 26 and vertical conductive layers 28 formed within insulating or dielectric material 30. Bump 22 is aligned with conductive layer 26 to mount semiconductor die 10 to substrate 24. Bump 22 is brought into contact with conductive layer 26 and reflowed to metallurgically and electrically connect the bump to the conductive layer, as shown in FIG. 1b. Substrate 24 provides structural support and electrical interconnect for semiconductor die 10.
The bumped semiconductor die 10 has a problem with delamination or damage of the extremely-low dielectric constant (ELK) interlayer dielectric layer (ILD) around bump area. When the semiconductor wafer is subjected to thermal stress during the reflow process, the ELK ILD delamination or damage can occur which causes defects in the semiconductor die.